AWS Batch

It is a regional service that simplifies running batch jobs across multiple AZs within a region.

Features

Batch manages compute environments and job queues, allowing you to easily run thousands of jobs of any scale using EC2 and EC2 Spot.

Batch chooses where to run the jobs, launching additional AWS capacity if needed.

Batch carefully monitors the progress of your jobs. When capacity is no longer needed, it will be removed.

Batch provides the ability to submit jobs that are part of a pipeline or workflow, enabling you to express any interdependencies that exist between them as you submit jobs.

Components

Jobs

Job Definitions

Job Queues

Compute Environment

Jobs

A unit of work (such as a shell script, a Linux executable, or a Docker container image) that you submit to Batch.

Jobs can reference other jobs by name or by ID, and can be dependent on the successful completion of other jobs.

Job types

Single for single Job

Array for array Job of size 2 to 10,000

An array job shares common job parameters, such as the job definition, vCPUs, and memory. It runs as a collection of related, yet separate, basic jobs that may be distributed across multiple hosts and may run concurrently.

Batch lets you specify up to five distinct node groups for each job. Each group can have its own container images, commands, environment variables, and so on.

Each multi-node parallel job contains a main node, which is launched first. After the main node is up, the child nodes are launched and started. If the main node exits, the job is considered finished, and the child nodes are stopped.

Not supported on compute environments that use Spot Instances.

Dependencies

A job may have up to 20 dependencies.

For Job depends on, enter the job IDs for any jobs that must finish before this job starts.

(Array jobs only) For N-To-N job dependencies, specify one or more job IDs for any array jobs for which each child job index of this job should depend on the corresponding child index job of the dependency.

(Array jobs only) Run children sequentially creates a SEQUENTIAL dependency for the current array job. This ensures that each child index job waits for its earlier sibling to finish.

States

SUBMITTED – a job that has been submitted to the queue, and has not yet been evaluated by the scheduler.

PENDING – a job that resides in the queue and is not yet able to run due to a dependency on another job or resource.

RUNNABLE – a job that resides in the queue, has no outstanding dependencies, and is therefore ready to be scheduled to a host. Jobs in this state are started as soon as sufficient resources are available in one of the compute environments that are mapped to the job’s queue.

STARTING – jobs have been scheduled to a host and the relevant container initiation operations are underway.

RUNNING – the job is running as a container job on an Amazon ECS container instance within a compute environment. When the job’s container exits, the process exit code determines whether the job succeeded or failed. An exit code of 0 indicates success, and any non-zero exit code indicates failure.

SUCCEEDED – the job has successfully completed with an exit code of 0. The job state for SUCCEEDED jobs is persisted for 24 hours.

FAILED – the job has failed all available attempts. The job state for FAILED jobs is persisted for 24 hours.

You can apply a retry strategy to your jobs and job definitions that allows failed jobs to be automatically retried.

You can configure a timeout duration for your jobs so that if a job runs longer than that, Batch terminates the job. If a job is terminated for exceeding the timeout duration, it is not retried. If it fails on its own, then it can retry if retries are enabled, and the timeout countdown is started over for the new attempt.

Job Queues

This is where a Batch job resides until it is scheduled onto a compute environment.

You can associate one or more compute environments with a job queue.

You can assign priority values for the compute environments and even across job queues themselves.

The Batch Scheduler evaluates when, where, and how to run jobs that have been submitted to a job queue. Jobs run in approximately the order in which they are submitted as long as all dependencies on other jobs have been met.

Compute Environment

A set of managed or unmanaged compute resources (such as EC2 instances) that are used to run jobs.

Compute environments contain the Amazon ECS container instances that are used to run containerized batch jobs.

A given compute environment can be mapped to one or many job queues.

Managed Compute Environment

Batch manages the capacity and instance types of the compute resources within the environment, based on the compute resource specification that you define when you create the compute environment.

You can choose to use EC2 On-Demand Instances or Spot Instances in your managed compute environment.

ECS container instances are launched into the VPC and subnets that you specify when you create the compute environment.

Unmanaged Compute Environment

You manage your own compute resources in this environment.

After you have created your unmanaged compute environment, use the DescribeComputeEnvironments API operation to view the compute environment details and find the ECS cluster that is associated with the environment and manually launch your container instances into that cluster.

Security

By default, IAM users don’t have permission to create or modify AWS Batch resources, or perform tasks using the AWS Batch API.

Take advantage of IAM policies, roles, and permissions.

Monitoring

You can use the AWS Batch event stream for CloudWatch Events to receive near real-time notifications regarding the current state of jobs that have been submitted to your job queues.

Events from the AWS Batch event stream are ensured to be delivered at least one time.

CloudTrail captures all API calls for AWS Batch as events.

Pricing

There is no additional charge for AWS Batch. You pay for resources you create to store and run your application.

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